Electric discharge device



April 26, 1949. w H T'EARE ELECTRIC DISQHARGE DEVICE Filed Dec. 14, 1944 WIm/entor:

illiam HT are,

His Attorney n 1111111111111'111111 l Il n '1,1111 l Irl ij'atented pr. 26,1949

UNTED STATES PATENT @FFME ELECTRIC DISCHARGE DEVICE William H. Teare, Ballston Lake, N. Y., assigner to General Electric Company, a corporation of New York Application December `'14, 1944, Serial No. 568,085

' 11 Claims.

My invention relates to electric discharge devices and more particularly to improved electrode mounting arrangements for high frequency discharge devices of themagnetron type.

In the design of higher frequency discharge devices, the smaller dimensions encountered render it diiiicult to provide structures which may readily be assembledand which will insure the required positional accuracy regardless of the skill of the assemblyman. In high frequency electric discharge devices of the magnetron type, it is particularly diicult to provide a structure for mounting the cathode and the space resonant anode structure which maintains axial alinement of the anode and cathode and which does not distort to an undesirable extent the magnetic field in the interelectrode space.

It is an object of my invention to provide a new and improved electric discharge device.

It is another object of my invention to provide a new and improved electrode mounting structure which insures accurate positional relationship between the electrodes.

A It is another object of my invention to provide an improved electrode mounting structure which insures adequate cooling of the anode structure.

It is a still further object of my invention to provide an improved electrode mounting for magnetrons which minimizes the distortion of the magnetic eld in the interelectrode space.

In the illustrated embodiment of my invention a magnetron of the metal envelope, internal permanent magnet type is provided with novel anode and cathode structures supported from a flange carried vby the side wall of the envelope. The anode and cathode structures are both positioned by engagement with accurately linished surfaces on an insulating ring. The accuracy of the iinal alinement of the electrodes is determined solely by the accuracy of the nished surfaces on the insulating ring and the engaging portions of the anode and cathode structures. Since all of these factors are determined in the production of the parts involved, the positional relationship of the parts is not dependent upon accurate assembly.

For a better understanding of my invention, reference may be had to the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims. In the drawing, Fig. 1 is an elevational view, in section, of a magnetron embodying my invention; Fig. 2 is a sectional view taken along the line 2- 2 of Fig.`1 with the upper magnet removed;'Fig.--3i's a perspective -view of the anode and cathode subassemblies, and Fig. 4 is an enlarged detailed view of the cathode support.

I have shown my invention embodied in a magnetron device of the sealed metal envelope, internal permanent magnet type. Referring now to the drawing, the envelope comprises a cylindrical portion I of steel tubing closed at opposite ends by end plates 2 and 3 which may to advantage be Welded to anges formed on the opposite ends of the tube I. Internal end plates are welded to the plates 2 and 3 and provided with passages 5 which provide free communication between an exhaust tubulation 6 formed on the end plate 3 and the interior of the envelope I. The anode and cathode structures of the device are supported in the central portion of the cnvelope by a ange member I which is welded or otherwise secured to the wall of the envelope and is provided with an inwardly extending portion 8 to which the electrode assembly is secured. The cathode assembly includes a cylindrical turned sleeve S of nickel or other suitable material on the outer surface of which is applied a coating of thermionically emissive material such as a mixture containing one or more of the alkaline earth oxides. The cathode 9 is provided at one end with a flange I0 which provides an end shield for the interelectrode space. The other end is provided with an accurately finished surface II of larger diameter than the active portion of the cathode and which is received in an opening formed in the central portion of a supporting disk or spider I2 for the cathode structure. The disk I2 is preferably a stamping of essentially nonmagnetic sheet metal, such as tantalum, and is provided with three angularly spaced mounting arms I3 for securing the disk to a supporting ring I4 which may to advantage be formed of an insulator such as alumina. Tantalum has substantially the same thermal expansion characteristics as alumina so that a tight t may be employed without introducing large stresses with changes in temperature. The arms I3 are formed during the stamping operation to provide vertical shoulders I5 which engage the inner surface of the ring I4 to position the disk I2 accurately with respect to the inner surface of the ring I4. A larger flange I6 on the upper end of the cathode 9 is Welded to the upper surface of the disk I2 to secure the cathode in position. As a means of heating the cathode element, a small fragmentary heater I'I is provided within the cathode sleeve, with one end secured to the sleeve and the other end extending from the upper end of the sleeve, where it is secured to a strap conductor I8 which is secured in insulated relation with respect to the supportlng disk I2 by one of the fastening bolts I9. The bolt I9 passes through a clearance hole in mounting arm I3 and is insulated from the arm by a suitable insulating washer 20. Other fastening bolts I8 secure the remaining arms I3 to the ring I4. As indicated most clearly in Fig. 4, the upper face of the ange I6 in the cathode sleeve is recessed at 2l to allow a small space between the cathode and the heater conductor I8 while maintaining the upper surface of conductor I8 ush with the surface of the disk in the central portion of the cathode assembly.

The anode employed in the illustrated embodiment of my invention is provided with a plurality of space resonant cavities arranged symmetrically about a central opening. Referring to the drawing, a disk or block of copper 22 is provided with a plurality of vanes 23 which extend radially inwardly and define a generally circular opening 24 in which the cathode 9 is received, and which defines with the cathode 9 the interelectrode space of the device. As is clearly visible in Fig. 3, the vanes define a plurality of wedge-shaped openings in the anode structure, which, as is well understood, function as a plurality of coupled tuned circuits. The anode body or disk 22 is provided with three radially extending arms 24a, which are supported on the upper face of the flange 8 and which are secured thereto by mounting bolts 25 which also pass through openings 25d in the ring I4. In order to position accurately the anode structure with respect to the insulating supporting member I4, and as a result to position the anode structure relative to the cathode, I provide a positioning disk 26 which is preferably formed of molybdenum. The centering disk 26 should be preferably nonmagnetic, and of the same or nearly the same thermal expansion as the insulating ring I4. The disk 26 surrounds a central or hub portion 2T of the anode and is held in assembled relation by deforming the upper edge of hub 21 with a punch as indicated at 28.

An output connection for extracting high frequency energy from the device is provided by a Wave guide 29 having an opening 30 of rectangular cross section formed therein. As indicated in Fig. 3, the opening in the wave guide is of progressively greater width in the direction away from the anode and, as indicated in Fig. 1, is provided with a quarter wave length filter 32 at its outer end. The wave guide is coupled to one of the wedge-shaped openings in the anode by a slot 33 interconnecting the inner end of the wave guide with the outer Wall of one of the resonant slots.

In assembly, the cathode 9 is secured to the supporting disk I2 which is, in turn, secured to the supporting ring I4 by fastening bolts I9. The anode assembly is then positioned in the enveiope with the arms 24a resting on the inwardly extending portion 8 of the flange member I with the end of the wave guide extending through an opening 34 in the side wall of the envelope and which is enclosed by a thimble 35 welded to the side wall of the envelope. The central portion of the end of the thimble 35 is a glass disk or window 36 located concentrically with respect to the wave guide. The thimble provides a suitable means for coupling the wave guide 29 to an output circuit. With the anode in position. the cathode assembly is placed within the envelope with the cathode 8 received in the opening 24 of the anode structure and the positioning disk 26 received within and tightly engaging the inner surface of ring I4. The arms 24a of the anode structure are in registry with holes 25a formed in ring I4 between the arms I3 of the cathode supporting disk. The bolts 25 secure both the anode and cathode assemblies securely to the flange. In order to provide clearance for the end of the wave guide, the cathode disk is provided with an opening 3l and the ring I4 is cut away as shown in Figs. 2 and 3.

A magnetic field in the interelectrode space between the anode and cathode is provided by a pair of permanent magnets 38 and 39 which are supported from the opposite ends of the envelope by retaining rings 40 which engage the ends of the magnets and are welded to the end plates 4 of the envelope.

The heater and cathode connections are provided by a pair of conductors 4I and 4Ia which are sealed through a glass member 43 which is, in turn, sealed to a flange 44 on the side wall of the envelope. Conductor 4I is connected by a flexible conductor 42 and terminal 42a to an arm of the cathode disk I2, while the other conductor 4Ia is connected by a flexible conductor 45 and terminal 45a connected with the heater I1 by the conducting' strap I8.

With the construction described above, the relative positions of the anode and cathode and the axial alinement of the cathode and the opening in the anode are determined solely by the accuracy of manufacture of the parts from which the assembly is made. The surfaces of the ring I4 are finished ground so that the opposite faces of the ring are parallel and are perpendicular to the inner cylindrical surface of the ring. The positioning disk 26 on the anode assembly and the arms 24a therefore, insure the desired location of the anode and the disk I2 with the positioning shoulder I5 engaging the inner surface of the ring I4 to insure the desired position of the cathode. This structure also provides for a good heat transfer connection between the anode structure and the flange member I which is welded to the envelope. Heat from the cathode is conducted by the disk I2 and the lead-in conductors which may be made heavy to increase the heat conducted. The absence of all conductors and supports in the direction parallel to the axis of the cathode cylinder makes it unnecessary to drill openings in the pole pieces, with the result that the magnetic eld in the interelectrode space is substantially parallel to the axis of the cathode. The construction is well adapted for either insulated anode or insulated cathode type tubes.

While I have shown and described a particular embodiment of my invention, it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention in its broader aspects, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A cathode structure including a supporting ring of insulating material, a sheet metal punching having an aperture therein, a plurality of positioning shoulders on said punching in spaced relation about said aperture, and a cathode supported on said punching in said aperture, said punching being supported from said ring with said shoulders in engagement with a positioning 'surface of said ring maintaining accurate positional relationship between said ring and said cathode.

` 2. A cathode structure including a supporting ring of insulating material, a sheet metal punching having an aperture therein and positioning surfaces on said punching in spaced relation about said aperture, and a cathode supported on said punching in said aperture, said punching being supported from said ring with said surfaces in engagement with a positioning surface of said ring maintaining accurate positional rela- ','tionship between said ring and said cathode.

3. An electric dis-charge device of the magnetron type comprising a generally cylindrical envelope. an anode structure having a central opening therein and a plurality of openings surrounding said central opening and providing a, plurality of coupled cavity resonators, a cathode positioned in said central opening, means supporting and positioning both said anode and said cathode from the side wall of said envelope intermediate the ends thereof, and means for producing a magnetic field in the space between said cathode and the walls defining the central opening of said anode comprising a pair of pole pieces supported from the ends of said envelope and terminating in closely spaced relation with the opposite ends of said cathode, said first mentioned means comprising a ring of insulating material positioned concentrically with the side wall of said envelope and intermediate the ends thereof, a first web member fixed to one end of said ring supporting said anode, a positioning member engaging the inner cylindrical surface of said ring positioning said anode, a second web member fastened to the other end of said ring supporting said cathode, and a plurality of positioning shoulders formed on said second web member engaging the inner cylindrical surface of said ring positioning said second web member.

4. An electric discharge device of the magnetron type comprising a generally cylindrical envelope, an anode structure having' a central opening therein and a plurality of openings surrounding said central opening and providing a plurality of coupled cavity resonators, a cathode 'positioned in said central opening and means supporting and positioning both said anode and said cathode from the side wall of said envelope intermediate the ends thereof, and means for prociucing a magnetic eld in the space between said -having an accurately finished inner cylindrical 'surface positioned concentrically with the side wall of said envelope and intermediate the ends thereof, a first web member fastened to oneend of said ring supporting said anode, a positioning member engaging the inner cylindrical surface of said ring positioning said anode, a second web member fastened to the other end of said ring vsupporting said cathode, and a plurality of positioning shoulders formedon said second web member and engaging the/inner cylindrical survface of said ring positioning said second web member.

5. An electric discharge device of the magnetron type comprising a generally cylindrical envelope, an anode structure having a central open- "cathode and the walls defining the central opening said central opening and providing a plu.- rality of coupled cavity resonators, a cathode positioned in said central openingl and means supporting and positioning both said anode'and said cathode from the side wall of said `envelope intermediate the ends thereof, and means adiacent said cathode for producing a magnetic field in the space between said cathode and the walls defining the central opening of said anode in a direction substantially parallel to the axis of said cathode terminating in closely spaced relation with the opposite ends of said cathode, said first mentioned means comprising a ring of insulating material positioned concentrically with the side wall of said envelope and intermediate the ends thereof, a first web member fastened to one end of Said ring supporting said anode, a positioning member engaging the inner cylindrical surface of said ring positioning said anode, a second web member fastened to the other end of said ring supporting said cathode, and a plurality of posi;- tioning shoulders formed on said second web member engaging the inner cylindrical surface of said ring positioning said second web member.

6. An electric discharge device of the magnetron type comprising an envelope, an anode including a plurality of cavity resonators surrounding a central opening, a cylindrical cathode, means supporting said anode and said`cathode in insulated relation from a side wall of said envelope with said cathode positioned in said central opening, and means including pole pieces extending in the direction of the axis of the cylindrical cathode for producing a magnetic eld between said anode and said cathode, said rst mentioned means comprising a ring of insulating material positioned concentrically with the side wall of said envelope and intermediate the ends thereof, a first web member fastened to one end of said ring supporting said anode, a positioning member engaging the inner cylindrical surface of said ring positioning said anode, a second web member fastened to the other end of said ring supporting said cathode, and a plurality of positioning shoulders formed on said second web member engaging the inner cylindrical surface of said ring positioning said second web member.

7. An electric discharge device comprising an anode having a circular opening therein, a cathode centered within said circular opening within said anode, supporting means having fastening surfaces and positioning surfaces positioned laterally of said anode and said cathode in spaced relation thereto, means engaging one of said fastening surfaces and said anode supporting said anode in spaced relation to said supporting means, means engaging one of said positioning surfaces and said anode positioning said anode within said supporting means, means engaging one of said fastening surfaces and said cathode supporting said cathode in spaced relation to said supporting means, and means engaging one of said positioning surfaces positioning said cathode centrally within said circular opening in said anode.

8. An electric discharge device comprising a generally annular anode having a circular opening therein, a cathode centered within said circular opening within said anode, supporting means having fastening surfaces and positioning surfaces surrounding said anode and said cathode in spaced relation thereto and positioned gener,- ally in the plane of said anode, means engaging one of said fastening surfaces and said anode supporting said anode in spaced relation to said supporting means, means engaging one of said positioning surfaces and said anode positioning said anode within said supporting means, means engaging one of said fastening surfaces and said cathode supporting said cathode in spaced relation to said supporting means, and means engaging one of said positioning surfaces positioning said cathode centrally within said circular opening in said anode.

9. An electron discharge device comprising, an anode of generally annular configuration, a cathode centered within said anode, an annular support of insulating material positioned concentrically about said anode and said cathode in spaced relation thereto, means engaging said support and said anode positioning said anode centrally of said support and in spaced relation thereto, and means engaging said Support and said cathode positioning said cathode centrally within said anode, said rst mentioned means comprising a web member fastened to one end of said annular support and a, positioning member engaging the inner surface of said annular support, said second mentioned means comprising a web member fastened to the other end of said annular support and a plurality of positioning shoulders formed thereon and engaging the inner surface o1 said annular support.

10. An electron discharge device comprising, an envelope, an anode, a cathode in spaced relation to said anode, an annular support of insulating material supported from the side wall of said envelope intermediate the ends thereof, means engaging said support and said anode positioning said anode centrally of said support and in spaced relation thereto, and means engaging said support and said cathode positioning said cathode in spaced relation to said anode, said first mentioned means comprising a web member fastened to one end of said annular support and a positioning member engaging the inner surface oi said annular support, said second mentioned means comprising a web member fastened to the other end of said annular support and a plurality of positioning shoulders formed thereon and engaging the inner surface of said annular support.

11. An electron discharge device comprising, an anode of generally annular configuration, a cathode centered within said anode, an annular support of insulating material positioned concentrically about said anode and cathode in spaced relation thereto, said support having an inner cylindrical surface and end surfaces perpendicular thereto, means engaging said support and said anode positioning said anode centrally of said support and in spaced relation thereto, means engaging said support and said cathode positioning said cathode centrally within said anode, said first mentioned means comprising a web member fastened to one of the end surfaces of said annular support and a positioning member engaging the inner cylindrical surface thereof, said second mentioned means comprising a web member fastened to the other end of said annular support and a plurality of positioning shoulders formed thereon and engaging the inner cylindrical surface of said annular support.

WILLIAM H. TEARE.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,555,677 Leblanc Sept. 29, 1925 1,813,593 Walton July 7,1931 1,901,703 Crowley Mar. 14, 1933 1,963,254 Urmson June 19, 1934 2,084,867 Pring et al June 22, 1937 2,115,521 Fritz et al Apr. 26, 1938 2,161,005 Bieling June 6, 1939 2,282,856 Engbert May 12, 1942 2,305,781 Helbig Dec. 22, 1942 2,324,166 McLaughlin July 13, 1943 2,406,276 White Aug. 20, 1946 2,406,277 Bondley Aug. 20, 1946 FOREIGN PATENTS Number Country Date 509,102 Great Britain July 11, 1939 Certificate of Correction Patent No. 2,468,576.

April 26, 1949.

WILLIAM H. TEARE It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 2, line 53, for the Word fragmentary read jilamentary; and that the said Letters Patent should be read With this correction therein that the same may conform to the record of the case in the Patent Oiiice.

Signed and sealed this 25th day of October, A. D. 1949.

THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

